1. Technical Field
The present disclosure relates generally to a method and apparatus for thermal treatment of tissue, and, more particularly, to a method and apparatus for the hyperthermia treatment of prostatic tissue.
2. Description of Related Art
Benign prostate hyperplasia (BPH) or hyperplasia affects over one out of every two males over the age of fifty. BPH is the non-cancerous enlargement of the prostate gland and is characterized generally by a constriction of the urethra by the prostate gland. An array of symptoms are associated with BPH including frequent urination, difficulties in urinary flow and associated pain.
Generally there are two primary methods for treating BPH, namely, drug therapy and surgical intervention. Drug therapy incorporates the use of one or more drugs such as Proscar(trademark) and Hydrin(trademark) to either reduce the size of the prostate or to relax the urethral muscles thereby facilitating the normal functioning of the urinary system. Known drug therapies, however, are limited in their effectiveness and present many drug side effect concerns.
Surgical methods for treating BPH include transurethral resection of the prostate (TURP), transurethral incision of the prostate (TUIP), visual laser assisted prostatectomy (VLAP), balloon dilation and stenting. TURP is the most common method employed for BPH treatment today and involves the insertion of an electrosurgical cutting instrument through the urethral passage. The cutting elements of the instrument are positioned adjacent the prostate gland, and the instrument is energized such that the cutting elements selectively cauterize and resect tissue from the core of the prostate. The TURP procedure, however, has many side effects including bleeding, electrograde ejaculation, impotence, incontinence, edema and a prolonged recovery period for the patient. An example of an electrosurgical cutting instrument utilized in conjunction with a TURP procedure is disclosed in U.S. Pat. No. 5,192,280.
Transurethral incision of the prostate (TUIP) involves the use of an electrocautery device which is passed through the urethra. The device is employed to make multiple incisions in the prostate, thereby permitting the prostate to be displaced from the urethra wall to create an opening for urine flow. Success with the TUIP procedure is generally limited providing only temporary relief and requiring a subsequent repeat of the procedure in the future.
Visual laser assisted prostatectomy (VLAP) includes insertion of a laser catheter through the urethra and directing laser energy laterally through the catheter sleeve at the urethral wall and the prostatic tissue. The laser energy causes the tissue to coagulate. The coagulated tissue eventually necrosis from lack of blood flow and is naturally removed from the body. Drawbacks of VLAP include increased recovery time, acute pain and irritation, and undesired burning of the urethral wall. Examples of methods and apparatuses utilized in VLAP treatment of BPH are disclosed in U.S. Pat. No. 5,242,438 to Saadatmanesh et al. and U.S. Pat. No. 5,322,507 to Costello.
Balloon dilation procedures for BPH involve expanding and stretching the enlarged prostate with a balloon catheter to relieve pressure off the constricted urethra while stenting incorporates the insertion of tiny wire-mesh coils which expand into a scaffold to hold the urethra open. Balloon dilation and stenting, however, are only temporary procedures typically requiring follow up within a year period. In addition, stenting presents complications of stent migration and consequent irritation.
More recently, two new surgical developments, namely, transurethral microwave therapy (TUMT) and high intensity focused ultrasound (HIFU) have been developed for the treatment of BPH. In accordance with a TUMT procedure, a foley-type urethral catheter having a microwave emitting antenna at a probe end is inserted into the urethral passage for a period of time sufficient to treat the tissue by microwave radiation. Intraurethral applications of this type are described in U.S. Pat. Nos. 4,967,765, 5,234,004 and 5,326,343. The drawbacks of TUMT include the inability to focus the heat energy in the prostatic area and the inability to achieve high temperatures uniformly within the prostate.
High intensity focused ultrasound (HIFU) includes directing high intensity ultrasound waves at the prostate tissue to create heat in a precise area to coagulate and necrose tissue. A transurethral probe is utilized to create the ultrasound beams for both imaging and ablation of the prostatic tissue. Disadvantages of this procedure include the inability to directly focus the ultrasound energy at the prostatic tissue.
A more recent and encouraging form of treatment for BPH involves thermally treating prostatic tissue with radiofrequency electromagnetic energy. For example, one current technique, known as transurethral needle ablation (TUNA(trademark)), involves the transurethral application of a medical probe having a pair of monopolar RF needle electrodes at its distal end The probe is inserted into the urethra and advanced to a position adjacent the prostate. Thereafter, the RF needles are advanced to penetrate the urethral wall and access the prostatic tissue. A RF current is transmitted through each electrode and passes through the tissue to a grounding pad to form a necrotic legion which is eventually reabsorbed by the body. Apparatuses and methods for treating BPH with RF energy are disclosed in U.S. Pat. Nos. 5,366,490; 5,370,675; 5,385,544; 5,409,453 and 5,421,819.
Although the use of RF electromagnetic energy in treating BPH shows promise in effectively and permanently alleviating symptoms of BPH, there exists significant limitations in the current state of development of RF thermal treatment and instrumentation.
Accordingly, the present disclosure is directed to an apparatus and method for the thermal treatment of tissue, e.g., prostatic tissue, with RF energy. The apparatus permits enhanced control over deployment of the energy emitting electrodes to enable the surgeon to selectively focus and maintain the electromagnetic energy within a predetermined heating pattern thereby reducing the amount of damage to neighboring healthy tissue.
In one preferred embodiment, the apparatus for thermal treatment of tissue includes a handle dimensioned to be grasped with a single hand of a surgeon, an elongated portion extending distally from the handle and defining a longitudinal axis, at least one electrode extending within the elongated portion and movable between a non-deployed position and a fully deployed position, and a trigger mechanism associated with the handle and having a trigger operatively connected to the one electrode. The trigger is movable relative to the handle to selectively and incrementally move the one electrode between the non-deployed position and the fully deployed position. A ratchet mechanism is associated with the trigger mechanism to permit movement of the trigger in one direction corresponding to movement of the one electrode toward the fully deployed position and maintain the electrode in position while preventing movement of the trigger in a second direction. The ratchet mechanism may be selectively released by a release trigger which is mounted to the handle and operatively connected to the ratchet mechanism. The release trigger is movable to release the ratchet mechanism to thereby permit movement of the trigger in a second direction corresponding to movement of the one electrode to the non-deployed position.
In another preferred embodiment, the elongated portion of the apparatus is rotatable about the longitudinal axis to position the one electrode at a predetermined angular orientation with respect to the longitudinal axis. A rotatable control knob is associated with the handle and operatively connected to the elongated portion to impart rotational movement to the elongated portion. Irrigation conduits for supplying irrigation fluids for flushing and/or cooling of the tissue and an aspiration conduit may also be provided.